1. Field of the Invention
The invention relates to a controller for a vehicle power transmission system and, more particularly, to improvement for suppressing a feeling of strangeness that is experienced by a driver at the time of a return from a fail-safe state.
2. Description of Related Art
There is known a vehicle power transmission system in which a gear mechanism and a belt-type continuously variable transmission including an input-side sheave and an output-side sheave are provided in parallel with each other in power transmission paths between an input shaft and an output shaft. The vehicle power transmission system includes a switching mechanism that selectively establishes one of a first transmission path and a second transmission path. The first transmission path is a path through which torque input from the input shaft is transmitted to the output shaft via the belt-type continuously variable transmission. The second transmission path is a path through which torque input from the input shaft is transmitted to the output shaft via the gear mechanism. The vehicle power transmission system described in International Application Publication No. 2013/176208 is an example of the above vehicle power transmission system.
However, International Application Publication No. 2013/176208 does not describe anything about a fail-safe technique in the event of a failure of a hydraulic pressure output device that controls hydraulic pressure that is output to the input-side sheave.